1. Field of the Invention
The present invention relates to roll systems for roller hearth furnaces for thin slab casters and, more particularly, to roll systems including alternating rolls of dry rolls and fluid cooled rolls.
2. Background Information
In roller hearth furnaces for thin slab casters, a large number of rolls is required due to the relative thickness of the slab. Thin slabs cannot tread easily over large gaps between rolls. Conventionally, in roller hearth furnaces the rolls are either dry or fluid cooled. Dry rolls are conventionally made of a heat resistant cast alloy. Fluid cooled rolls generally have a water cooled shaft therein and may further include insulation and heat resistant, work supporting metal rings or tires. In these situations, the dry roll, as well as the tires of the water cooled rolls, have the tendency to pick up scale due to the high working temperature of the contact surface with the slab. The scale pickup leads to an associated marking or marring of the slab surface.
It is an object of the present invention to minimize the scale pickup problem and the associated marking problem of the slab surface and also minimize the heat losses due to the roll system.